1. Field of the Invention
The invention relates generally to the measurement of electrical characteristics of a liquid, and in particular, to the continuous monitoring of the electrical conductance and/or capacitance of a liquid product during a chemical processing of the liquid, and the automatic conversion of the characteristics measured to the value of these characteristics at a selected reference temperature of the liquid product.
2. Description of the Prior Art
During chemical processing employing nonaqueous liquids, such as alcohols, ketones, organic acids and other hydrocarbon liquid products produced by the petrochemical industry, it is desirable to continuously monitor the liquid during the processing operation to assure control of the process and determine its endpoint. Where one or more of the electrical properties of the liquid changes in value during the processing operation, the end point of the process can be determined by continuously monitoring one or more of these electrical properties of the liquid product. For example, U.S. Pat. Nos. 3,779,892 and 3,868,315, issued Dec. 18, 1973 and Feb. 25, 1975, respectively, to Eric O. Forster et al., disclose an electronic measuring technique for continuously measuring the difference between the electrical resistance (and capacitance) of asphalt during an oxidation process and a reference standard having a resistance (and capacitance) corresponding to the finished product, to stop the process when the asphalt being oxidized has the same resistance as the reference standard. However, since both the resistance and capacitance of a liquid changes with the temperature, the measuring technique disclosed in U.S. Pat. No. 3,868,315 is restricted to a process in which the liquid product being monitored is maintained at a constant and uniform temperature for which the resistance and capacitance values of the reference standard apply. The equipment required to maintain a liquid product at a constant and uniform temperature during a chemical process can be very costly, especially if the only reason for such tight temperature control is for prompt and accurate shutdown of the process, as determined by the electrical characteristics of the liquid. Also, some processes may be more effective if the temperature of the liquid product is varied during the process.